Category Archives: Security Learning

APT – What you need to know?


APT – Advanced Persistent Threat is the latest buzz word in the industry. Everyone who is in the Security Industry, professionals and business alike want to get into the bandwagon that is called APT. Security product vendors are all gearing to cater to “APT” and all their current product lines or future releases address APT in some form of the other. Now, the fever has spread to the IT Management as well and now they want their Security teams to detect and prevent APT. Even though the InfoSec public has caught up with it, how much thought have we put into understanding the magnitude of the problem at hand? Is it enough to just jump on to something without understanding it fully or do we need a more educated and intelligent decision making?

Let us find out more in this post!!!!

As always, I would like to define APT to start with. This is key because once the definitions are clear, all we would need is to align our thinking to that definition. Then, I will list down what flaws we have in our current approach towards security. Finally, I will try to list down as many possible solutions to the problem at hand.

Defining APT:
Simply put, APT is a Security Threat to the Enterprise (even End User for that matter) that is Advanced in execution that traditional security filters are not able to catch outright and is persistent enough that it keeps moving from one compromised target to another evading detection. 

Is it a technology of the future? – No, it is not. APT is nothing but a threat we are not trained to see. One of the main reasons why APT has been so successful in many organizations is the fact that we have an outdated security strategy. For example, we are keen on tracking a Data Exfiltration from a compromised machine. How do we do it today?

  • To start of with, we look for Data Loss Prevention Solutions and see which vendor is the market leader
  • Then we implement DLP solutions with basic policies for generic data loss (PDF, WORD DOC, XLS, Source Codes, Credit Card Numbers, PAN, PII etc)
  • We fine tune the DLP policies for our enterprise specifically and implement detection and prevention capabilities
  • We log the data from DLP solutions to SIEM and alert when something of interest happens.
  • In addition or In replacement, IDS/IPS rules will be implemented to identify data loss traffic based on REGEX file names etc.
  • In some cases we would also look at Traffic going to Blacklisted Domains and IP.
I am sure all of them or majority of the organizations do this to identify Data Exfiltrations. But  can all those organizations say that they are safe against APT? The answer is a SAD NO. The reason being, Known (Policy or Signature of What is Bad) is a drop, Unknown (Where APT works) is an Ocean. The threat landscape has evolved to exploit the Unknown, but we have not evolved to detect and respond to it. What is the solution for this problem?
There are several solutions being proposed by several people in the industry.  In my opinion one of the most important solutions is to do behavior profiling and Anomaly Detection.
Now What is Behavior profiling?
Behavior Profiling – Every network, every segment of the network has a behavior profile that is deemed normal. Today how many of us know what our Network Segments look like in terms of Connections they accept, they deny, Traffic flowing within the segment, what are the most used protocols, what are not used, What size of packets flow, what outbound and inbound communications happen, Access in and out, Who is supposed to and Who is not etc etc.. I seriously doubt it. We are more concerned about getting the system up, providing the service it is deemed to provide. We seldom think about the Security Profile the segment has. Once we profile, we can identify several Anomalies.

Let us now take the same example of Data Exfiltration and see how Behavior profiling would help:

  1. We would have complete details about where sensitive data is residing, the VLAN, the Server, the Folder, The file, The DB tables etc.
  2. To the Sensitive Machine/Network/Data, We would know who has access to and Who does not?
  3. We would also track who has a copy of that data – what is the machine, where is it residing (desktop, laptop, mobile) etc.
  4. The data usage by which team, which individuals etc are also profiled and that would give us the subset of people handling that sensitive data
  5. Any theft of that data would be through one of the above actors/entities.
  6. Tracking each of their machines activity over time would give us a Normal behavior profile.
  7. Digital Markers on such sensitive data can also be placed by the corporations to track data use/flow
  8. We can also track periodicity of data access, time of access, track the data changes etc through Digital Markers
  9. Any deviations from Normal behavior is a potential Data Exfiltration action and needs to be investigated
  10. Behavior profiles thus created can be used in addition to Signature based detection

This requires intimate co-ordination with various teams and also requires great understanding of what your Network does, what it is supposed to do. This while being the most logical is the most challenging to implement and thus the most rewarding as well. Behavior profiling is being used in the Intelligence Community for a long time, but the Technology community is still to embrace this. Enterprise data is becoming critical and with threats like APT, our fundamentals are being questioned.

This approach can help after the fact but from preventing the occurrence a Long term solution is needed. From a long term perspective the only solution is building Networks and Applications (OS as well as Apps) from ground up to treat security as a embedded character and not an add on feature.

What are your thoughts on APT? How do you think we should change our Security thought process, technology and all to combat it? Sound on below!!!

How good is our current Security Strategy?


Few years ago, none of the “Hacktivist Groups” existed or even if they did, they lurked in the underworld. But today, they have the guts to come out in public and declare war on the Internet. They have also been very successful in bringing big corporations loss in terms of data and money. And how much wager would you like to place that this is just the beginning. This begs us to the very question – How good is our current Security Strategy? 

Traditionally we have been building the Security Regime using one or both of the approaches in tandem: Known Bad Security (Blacklisting) and Known Good Security (Whitelisting). To all those signature and behavior based thinkers, don’t fret, for this approach is a superset of Signature and Behavior based approach.

First let us look at Known Bad Security or Blacklisting:
One of the things we are very good at is, “KNOWN BAD” detection and response. By this I mean, we are good at identifying Vulnerabilities based on Vendor releases, patching them once the vendor releases the patches, updating AV/AS, IDS/IPS, Content Filtering etc to protect against exploitation. This is what “KNOWN BAD” Security is all about. You know it is bad and you defend against it. But a recent survey by Verizon shows that only 1% of the total data breaches are identified by IDS/IPS or AV solutions. This is a clear indicator that Signature based detection or Blacklisting based response is not giving us the results. So even though we are very good at Known Bad Security, we are being compromised day in and day out!!!!

Known Good Security or Whitelisting is just the opposite of Known Bad:
By this I mean, we identify and maintain a list of KNOWN GOOD items in our IT Infra. What connections are good, What users are good, What files are good, What is allowed, What is unauthorized etc as our data points for Known Good Security. Based on this data, we identify Security Abnormalities, anomalous pattern detection etc that don’t conform to the Whitelist and go after them as Rogues/Attackers. We investigate them, if found bad follow remediation process for them or if found good add them to the Whitelist. Once we know What is bad, we automate it by feeding to the Blacklist detection and Response. This while being effective is a slow and tedious process thereby giving gracious amounts of time for an attacker to wreak havoc.

Some Good, Some Bad:
Most of the Enterprises today effectively use a combination of Blacklisting and Whitelisting to achieve their Information Security needs. But based on the threats being propagated today, we can say with enough confidence that this approach is failing. The main reason for the failure is that, “Actual Good and Actual Bad are way more than Known Good and Known Bad”. Since we are unable to quantify these numbers scientifically, we end up doing good of nothing.

What we lack?
Our current strategy towards security has some gaping holes. Some of them are listed below:

  • Over Relying on External Sources: We still rely on Vendor input, community input and other public disclosures to define Blacklisting. One vendor’s threat detection efficiency is different from the other. One vendor might rate a Malicious Code as High Severity, but the other may rate it as Low. This kind of disparity does not help in determining what is “Actually bad”.
  • Poor Knowledge of our environment: How many times have you identified a Security incident and while investigating found out something new about the environment. I can bet that it is literally every time. Without knowing the exact nature of our environment, we would not be able to do any effective Whitelisting. Without effective Whitelisting, effective Blacklisting also is impacted
  • One cure for All diseases: We think that if one organization is compromised by a specific exploit, it is applicable to all. We seldom think or evaluate the Controls we have may differ significantly from the controls other organizations have. Security should be tailored to suit not vice-verse.
  • Once we Whitelist something, we never re-evaluate. We perceive that “it is clean” and pay little attention till hell breaks loose. This is more related to human nature than anything else I guess. Once we “move past” we never look back. This will hurt us because, a whitelist today might turn bad tomorrow due to IT dynamics, thereby leading to an exploit.
  • We live by and die by More tools – more security, Latest signatures – more protection, more resources – more coverage, more training – more knowledge. Most organization just buy Security tools or technologies to fill a check box in their Audit/Compliance needs. If the company execs have caught wind of some Security attack that happened at some other company, they are paranoid that it will happen to them as well. Hence “Gimme more security” approach.
  • More the HooHa More Serious the Threat: The amount of publicity received is directly proportional to the severity of the threat. We would have several other threats in our environment, several gaps we need to fix, but we would still look for the famous Conficker, Flame, Stuxnet, Aurora, Zeus etc. Even though some of them were big in terms of spread, every organization had different infection rates.
  • We still think Security as a Operations function. We still go by the number of Alerts worked, number of incident raised, time to solve, time to respond etc. Security is more Analytical, investigative field. Looking beyond the noise, finding the needle in the haystack, attacker attribution and all sound cool on paper, but to bring it to reality the current strategy doesn’t help.
  • Security is not a culture. In everyday life, you lock the front door, keep important things in a safe, put on safety gear, wear a seat belt etc, but we don’t treat our IT systems development, implementation and management with a Security mindset. Bad products are developed, bad implementations happen, bad administration and monitoring happen, and finally mistakes from people too happen, leading to a Security breach, data theft and loss.

I am sure there is more than the above list in terms of flaws in our current strategy. What do you think? Please comment on!!!

 

SIEM Use Cases – What you need to know?


My previous post “Adopting SIEM – What you need to know” would give a better starting point if you are new to SIEM and want to implement it in your organization. If you already use/manage/implement a SIEM, then read on.
To start with, SIEM tools take a lot of effort to implement. Once implemented, they need to be taken care like babies. If care is not given, within a few months you would be staring at a million dollar museum artifact. Now there are two parts of care:

  1. Making sure that the systems are updated regularly, not only for patches and configurations but also the content put in them.
  2. Second and the most important part is making the SIEM relevant to the current Threat Landscape.

Anyone who has worked on SIEM for some time would agree with me, that Administration is generally easier compared to making the system relevant to the Threat Landscape. Before people hit me with “Administration is also a pain”, I would like to offer a defense saying that mostly, all SIEM products have documentation attached that give fair amount of information on how to install, update, upgrade and operate these systems. However, Translating Threat Landscapes to nuts and bolts for SIEM purposes is the biggest challenge and there are no guides that can help do that.

In this blog post, my attempt is to make this translation as easy as possible. In SIEM parlance, we call the translation as a Use Case. If there is well-defined Use Case, implementing them, responding to them and managing them would become easier. Such Use Cases would eventually become the cornerstone on which a SOC (Security Operations Center) is built. As usual, I would like to start with defining a Use Case, running through its stages and then finally wrapping it up with an example. So here we go.

Use Case Definition: A Use Case by definition is nothing but a Logical, Actionable and Reportable component of an Event Management system (SIEM). It can be either a Rule, Report, Alert or Dashboard which solves a set of needs or requirements.

A Use Case is actually “developed” and this development is a complete process and not just a simple task. Like a mini project it has several stages. The various Stages involved in Use Case Development are as follows:

  • First stage is the “Requirements”Definition. It can be any of the following high level requirements and is unique to every company:
    1. Business
    2. Compliance
    3. Regulatory
    4. Security
  • Once the requirements are finalized, the next stage would be to “Define the scope” of the requirement. This would typically mean the IT Infrastructure that needs to be protected and is a high priority for the specific requirement.
  • Once the scope is finalized, we can sit down and list the “Event Sources” that would be required to implement the Use Case. These would be Log Data, Configuration Data, Alert Data etc coming out of IT Systems under the above Requirements Scope.
  • The next stage would be to ensure that the Event Sources are going through “Validation Phase” before use. Many times, we would have an Event source but the required data to trigger an Event may not be available. This needs to be fixed before we proceed with the Use Case development.
  • Post validation, we need to “Define the Logic”. This is where we exactly define what and how much data is needed to alert along with the Attack Vector we would like to detect.
  • Use Case “Implementation and Testing” is the next stage. This is where we actually configure the SIEM to do what it does best – Correlation and Alerting. During Implementation the definition of the desired output can also be done. The output can be one of the following:
    1. Report
    2. Real Time Notification
    3. Historical Notification
  • Once implementation is done, we need to “Define Use Case Response” procedures. These procedures help you to make the Use Case Operational.
  • Finally, Use Case “Maintenance” is an ongoing process to keep the Use Case relevant by appropriate tuning.

Now that we have defined in detail the Use Case Development methodology, it is time to take an example and see how this actually looks in Real Life Implementation terms.

The Requirement: Outbound Spam Detection.
The Scope: Mail Infrastructure, End User Machine, Security Detection Infrastructure
The Event Source:
  • IDS/IPS at Network and Host – Signature Based Detection
  • Mail Hygiene or Mail Filtering Tools – Signature Based Detection
  • Events from Network Devices – Traffic Anomaly Based Detection
  • Events from End User Detection tools – Signature and Traffic Anomaly Based Detection

The Event Validation: The devices logging to SIEM should be normalized and parsed properly. Typically, SIEM products would allow Content development based on their native Field Mappings (Through Parsing). If the fields are not mapped, then the SIEM does a poor job of Event Triggering and Alerting. The required fields for the above Use Case would typically be Source IP, Source user ID, Email Addresses, Target IP, Host information of Source and Target, Event Names for SPAM detection, Port and Protocol for SMTP based traffic detection etc.

Use Case Logic Flow: The Logic definition is something unique to the environment and needs to be defined accordingly. The logic can be either Signature based or behavior based. You can have it restricted to certain subset of data (based on the Event Sources above) or expand it to be more generic. Some samples are given below:
  • One machine doing Port 25 Outbound connections at the rate of 10 in a minute
  • SPAM Signatures originating from the same source from IDS/IPS, Mail Filter etc having the same destination Public domain
  • SYN Scans on port 25 constantly from a single source etc

Implementation and Testing: Once the logic is defined, Configuration of SIEM and tuning the implementation to trigger more accurately is the next phase. After Implementation of the Use Case, we would need several iterations of Incident Analysis along with data collection to ensure that the Use Case is doing what it is intended to do. This is done at the SIEM level and may involve aggregation, threshold adjustments, logic tightening etc.

Use Case Response: After implementation, the Use Case need to be made as a valuable resource by Defining a Use Case Response. This is the stage where you would define “What action needs to be taken and how it needs to be taken”. You can look at Episode 4 of my Security Investigation series to get an idea of how to Investigate SPAM cases. Other Security Investigation Series Articles are located here – Security Investigation Series.

SIEM Use Cases are really the starting point for good Incident detection. If you want to run a SOC, having well-defined SIEM Use Cases would ease management and increase efficiency of Operations. This post is my humble attempt to simplify and regularize Use Case development for SIEM implementations.

As always, I would love to hear comments and thoughts on this topic.